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Pet 8296 blown fuse with monitor connected, and no chirp sound

Just because an EPROM is marked as FAST doesn't mean it is. An STS M2716-1F1 is still 350 ns.

Who knows what an M2716A-AF1 actually is without the datasheet...

I would just get a proper device programmed if you suspect that the device is faulty...

Dave
 
Dave, for the moment i have resolved with this ebay seller, it have to program new 74s288 with my file and send to me:

www.ebay.it

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The new chip i have buyed i resell it in future, i have ordered 2 new programmet 74S288 for 35 euro shipped, good for me.

Emanuel
 
Chip arrived and installed, now is complete and working.

But now, keyboard don't work, any key is not working. I have connected it only now with computer full working, not in all other tests Probably another fault and i think so is a 6520 faulty, or 74ls145.

Tomorrow i check.
 
Excellent.

The PIA is an easy check. The 74LS145 less so because it has open collector outputs so you need a 10k pull-up resistor to +5V to test the outputs in addition to your oscilloscope.

I assume you have a flashing cursor on the screen (indicating the presence of interrupts)?

Dave
 
Hi dave, both are good only keyboard contact very poor, now it is working, but i have a question, this is a german version 8296 with qwertz keyboard, but any special character on the right of keyboard not corresponding tu key or correct character, the char rom is original and edit rom too, only kernal/basic rom are replaced with new 27128 eprom, is possible this is a cause of wrong key pressed?
 
Quite possibly.

If you have a German keyboard you really should have the German character ROM and EDIT EPROM.

Dave
 
It might be better as a new topic to save mixing faults.

But, if you have finished the last one - it is your choice...

Dave
 
The last one is ok and now in spain, i have selled it because i have this another one 8296D-

Ok open new topics.
 
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